Chemistry Alkanes/Alkenes

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Experiment: Comparing reactivities of alkanes and alkenes
Aim: To compare the reactivities of an alkane and an alkene with bromine water and a solution of potassium permanganate (KMnO4). Equipment:
4 test tubes
Test-tube rack
4 pipettes
Safety: safety glasses must be worn to prevent injury to the eyes. Ensure room is well ventilated whilst using the hydro carbons. Method:
1.Place 1 ml of sample A (cyclohexane) into a test tube containing 4 mls of the bromine water solution. Record observations of any reaction. 2.Place 1 ml of sample A (cyclohexane) into a test tube containing 4 mls of the potassium permanganate solution. Record observations of any reaction. 3.Place 1 ml of sample B (cyclohexene) into a test tube containing 4 mls of the bromine water solution. Record observations of any reaction. 4.Place 1 ml of sample B (cyclohexene) into a test tube containing 4 mls of the potassium permanganate solution. Record observations of any reaction.

RESULTS
SampleReaction with br2 waterReaction with acidified KMnO4Hydrocarbon (alkane/alkene) ANo reaction, both liquids immiscible, br2 water kept its yellow colourNo reaction, both liquids immiscible, KMnO4 solution kept its purple colourAlkane BBoth liquids reacted, causing 2 immiscible transparent liquidsBoth liquids reacted, causing the KMnO4 solution to change to a brownie red colourAlkene

Analysis:
The positive reaction in the experiment was the reaction between the alkene (cyclohexene) and both the bromine water and the potassium permanganate solution. Below is a balanced structural formula for the reaction between cyclohexene and the bromine water:
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